An element that adjusts amount of light transmission for a display device, a light-adjusting filter, and the like, is sold in a market.
A device for displaying information (a display device) such as a television, a monitor for a personal computer, and a display for mobile phone is one of essential devices in recent information society. A light-adjusting filter that adjusts amount of light irradiated from outside, an anti-glare mirror, and the like have similar effect to a curtain being capable of adjusting light irradiated from outside in a space of house, car, airplane, etc. Thus, they are very useful in life.
A display type of a display device can be generally divided into a reflection type, a transmission type, and a light emission type. A person who manufactures a display device generally selects a preferable display type for manufacturing a display device by assuming an environment of usage for a display device.
Recently, portability of a display device has been enhanced by miniaturizing and thinning a display device, so that a display device has been often used in an environment of different brightness levels and demands of users for a display device have been also diversified. As a mode for a display device, for example, a mirror surface state of a display screen as well as a bright state and a dark state has been demanded. This is the same as a light-adjusting filter, and the like.
As a related technology, for example, an electrochromic mirror in which a mirror layer is formed on one substrate of a pair of substrates is disclosed in a patent document 1 described below.